Fcepsilon-PE chimeric protein for targeted treatment of allergy responses a method for its production and pharmaceutical compositions containing the same

ABSTRACT

The present invention generally relates to a new approach for thetherapy of allergic responses, based on targeted elimination of cells expressing the FcεRI receptor by a chimeric cytotoxin FC 2′-3 -PE 40 . A sequence encoding amino acids 301-437 of the Fc region of the mouse IgE molecule was genetically fused to PE 40 ′—a truncated form of PE lacking the cell binding domain. The chimeric protein, produced in  E. coli,  specifically and efficiently kills mouse mast cell lines expressing the FcεRI receptor, as well as primary mast cells derived from bone marrow. The present invention provides a chimeric protein for targeted elimination of FcεRI expressing cells especially useful for the therapy of allergic responses. The said chimeric protein is comprised of a cell targeting moiety for FcεRI expressing cells and a cell killing moiety. The preferred killing moiety is the bacterial toxin Pseudomonas exotoxin (PE). This Pseudomonas exotoxin is a product of  Pseudomonas aeruginosa.  The present invention also relates to a method for the preparation of said protein. This chimeric protein is prepared by genetically fusing the Fc region of the mouse IgE molecule to PE 40 , a truncated form of PE lacking the cell binding domain. The present invention also provides pharmaceutical compositions, for the treatment of allergic diseases and for the treatment of hyperplasias and malignancies, comprising as an active ingredient the above mentioned chimeric protein and a conventional adjuvant product.

FIELD OF THE INVENTION

[0001] The present invention generally relates to a novel approach for the therapy of allergic responses. More specifically the present invention relates to Fcε-PE chimeric protein for targeted elimination of FcεRI expressing cells, a method for its production, and pharmaceutical compositions containing the same. This chimeric protein is composed of cell targeting which is a part of IgE molecule linked to cell killing moieties for recognizing and distroying cells overexpressing the specific receptor. The killing moiety used in the chimeric protein of the present invention is the bacterial toxin Pseudomonas exotoxin (PE) (a product of Pseudomonas aeruginosa).

BACKGROUND OF THE INVENTION

[0002] About twenty percent of the world population suffers from various allergic diseases such as asthma, allergic rhinitis, food allergies, atopic dermatitis and anaphylaxis. The alarming increase in the prevalence of allergic diseases over the past decade has led to a clear need for more effective treatment.

[0003] The interaction between IgE and mast cells or basophils is the primary effector pathway in allergic responses. IgE binds to high-affinity receptor (FcεRI) for its constant region, found almost exclusively on the surface of these cells. The binding itself, in spite of the low dissociation rate, does not result in stimulation of the cell. However, cross-linkage of cell surface-bound IgE by multivalent antigen causes receptor aggregation, triggering explosive cellular degranulation whereby mediators of allergy such as cellular degranulation whereby mediators of allergy such as histamine and seretonin are released.

[0004] The fact that distribution of the FcεRI receptor is restricted to cells participating in an allergic response makes it an attractive candidate for targeted immunotherapy by chimeric cytotoxins. Chimeric cytotoxins are a novel class of targeted molecules constructed by gene fusion techniques. These molecules are composed of cell targeting and cell killing moieties, enabling them to recognize and distroy cells overexpressing specific receptors.

[0005] The bacterial toxin Pseudomonas exotoxin (PE) used in chimeric protein constructs, is a product of Pseudomonas aeruginosa. Having accessed the cytoplasm, PE inhibits protein synthesis by its ADP-ribosylation activity, thus causing cell death (Middlebrook, J. I., and Dorland, R. B. 1984. Bacterial toxins: cellular mechanisms of action. Microbiol. Rev. 48, 199.). Effective chimeric cytotoxins have been constructed by fusion of cDNAs encoding various growth factors or single chain antibodies with PE derivatives lacking intrinsic cell binding capacity. One of these chimeric proteins designated IL₂-PE₄₀, constructed to target and selectively eliminate activated T cells overexpressing IL₂ receptors, was shown to provide effective and selective immunosuppression in various models of autoimmune disorders, graft rejection and cancer (Lorberboum-Galski, H. 1994. Interleukin 2-Pseudomonas exotoxin A (IL2-PE40) chimeric protein for targeted immunotherapy and the study of immune responses. J. Toxicol.-Toxin Rewiewes, 13 (1), 105.).

[0006] The entire recombinant constant region of IgE (Fcε) expressed in bacteria, have an affinity for FcεRI receptor comparable to that of the native IgE, as well as the capacity to sensitize basophils for anti-IgE indused histamine release. When recombinant fragments of human Fcεexpressed in bacteria, were tested for receptor binding, a peptide corresponding to residues 301-376 at the junctions of domains 2 and 3 of the constant region was found to be sufficient for high-affinity binding to the receptor. It was also reported that ε-chain dimerization was not required for receptor binding (Helm, B., Marsc, P., Vercelli, D., Padlan, E., Gould, H., and Geha, R. 1988. The mast cell binding site on human immunoglobulin E. Nature 331, 180.).

[0007] The present invention generally relates to a novel approach for the therapy of allergic responses. At present the major known groups of drugs used in the treatment of asthma and allergic disorders are:

[0008] 1. β2 agonists—produce airway dilatation through simulation of β2 adrenergic receptors.

[0009] 2. Methylxantines—smooth muscle relaxants, produce bronchodilatation.

[0010] 3. Glucocorticoids—reduce inflammation.

[0011] 4. Cromolyn sodium—prevents mast cell degranulation.

[0012] 5. Antihistamines—prevents histamine action on it's target cells.

[0013] Although widely used, all of these drugs have notable disadvantages in regard to:

[0014] 1. Specificity: The action of all of these drugs (except cromolyn sodium) is not mast cell specific. Therefore, they can not prevent the release of allergy mediators but rather reverse or block the effects caused by their action. The treatment by these drugs is symptomatic, it can be started only after the onset of the allergic reaction and thus can't be used in a prophylactic manner.

[0015] 2. Toxicity: Being non-specific, these drugs exert their action on various tissues and organs causing serious side effects. The major side effect of B2 agonists is tremor, but they also cause cardiac arrhythmias; Methylxantines stimulate the central nervous system, causing nervousness, nausea, vomiting, anorexia, headache and cardiac muscle-causing tachycardia. At high plasma levels there is a danger of seizures and arrhythmias. Antihistamines affect the central nervous system, causing sedation. Steroids are most harmful, causing suppression of the pituitary-adrenal function, fluid and electrolyte disturbances, hypertension, hyperglycemia, increased susceptibility to infections, osteoporosis and arrest of growth in children.

[0016] 3. Duration of the effect: β-adrenergic agonists, aminoxantines and antihistamines are mostly short-acting drugs, and as such must be administered frequently. Steriods which are long-acting drugs, have also long induction time and are of little value in emergencies.

[0017] The only existing mast cell specific drug is Cromolyn sodium. This drug can be used prophilactically, essentially without side effects. However, it has a very short half life, very long induction time, it can be applied only locally and only part of the patients respond to it. All these make use of Cromolyn sodium very limited.

[0018] A number of attempts to interfere with interaction between IgE and it's high-affinity receptor, as a basis for anti-allergy therapy, have been reported in recent years. Recombinant peptides comprising structural elements from IgE (Helm, B., Kebo, D., Vercelli, D., Glovsky, M. M., Gould, H., Ishizaka, K., Geha, R., and Ishizaka, T. 1989. Blocking the passive sensatization of human mast cells and basophil granolocytes with IgE antibodies by a recombinant human ε-chain fragment of 76 amino acids. Proc. Natl. Acad. Sci. USA 86, 9465.) or FCεRI (Ra, C., Kuromitsu, S., Hirose, T., Yasuda, S., Furuichi, K., and Okumura, K. 1993. Soluble human high affinity receptor for IgE abrogates the IgE-mediated allergic reaction. Int. Immunol. 5, 47.;Haak-Frendscho, M., Ridgway, J., Shields, R., Robbins, K., Gorman, C., and Jardieu, P. 1993. Human IgE receptor a-chain IgG chimera blocks passive cutaneous anaphylaxis reaction in vivo. J. Immunol. 151, 351.) have been investigated as competitive inhibitors of the IgE-FcεRI interaction. Monoclonal antibodies generated against IgE (Baniyash, M., and Eshhar, Z. 1984. Inhibition of IgE binding to mast cells and basophils by monoclonal antibodies to murine IgE. Eur. J. Immunol. 14, 799) or FcεRI (Kitani, S., Kraft, D., Fischler, C., Mergenhagen, S. E., and Siraganian, R. P. 1988. Inhibition of allergic reactions with monoclonal antibody to the high affinity IgE receptor. J. Immunol. 140, 2585.), capable of blocking IgE binding to the receptor, without causing mast cell degranulation have also been tested. However, the affinity of IgE for FcεRI is very high (K_(M)=10⁻²⁰M), so that once it is bound to it's receptor, the IgE molecule remains attached to the cell membrane for several weeks. Moreover, mast cell can be activated at low receptor occupancy: the cross-linkage of as few as 5% of receptors is sufficient to cause mast cell degranulation. These two properties of the system impede inhibition by competitive agents, thus limiting their clinical value. Our anti-allergy molecule depends to a much lesser extent on the ability to compete with IgE. Once having entered the target cell through a non-occupied IgE receptor, the chimeric protein affects the target cell. Moreover, early expression of the receptor in the maturation course of mast calls should allow the elimination of immature target cells before they are capable of mediator release. As the receptor is not expressed on stem cells, no damage to bone marrow is expected on the whole.

[0019] The IgE system is quite complex and diverse. Interactions between IgE and its binding structures have many functions apart from the allergic response, some of which are only beginning to emerge. Monoclonal antibodies against IL-4, the IL-4 receptor or the low-affinity IgE receptor eliminate expression of IgE in mice but have more general immunosupressive effects. The advantage of the present invention in which the high-affinity IgE receptor is targeted and not the overall IgE system, is therefore evident.

SUMMARY OF THE INVENTION

[0020] The present invention generally relates to a new approach for therapy of allergic responses, based on targeted elimination of cells expressing the FcεRI receptor by a chimeric cytotoxin Fc_(2′-3)-PE₄₀. A sequence encoding amino acids 301-437 of the Fc region of the mouse IgE molecule was genetically fused to PE₄₀—a truncated form of PE lacking the cell binding domain. The chimeric protein, produced in E. coli, specifically and efficiently kills mouse mast cell lines expressing the FcεRI receptor, as well as primary mast cells derived from bone marrow.

[0021] The present invention provides a chimeric protein for targeted elimination of Fc<RI expressing cells especially usefull for the therapy of allergic responses. The said chimeric protein is comprisesd of a cell targeting moiety for the FcεRI expressing cells and a cell killing moiety. The preferred killing moiety is the bacterial toxin Pseudomonas exotoxin (PE). This Pseudomonas exotoxin is a product of Pseudomonas aeruginosa.

[0022] The present invention also relates to a method for the preparation of said protein. This chimeric protein is prepared by genetically fusing the Fc region of the mouse IgE molecule to PE₄₀, a truncated form of PE lacking the cell binding domain.

[0023] The present invention also provides a pharmaceutical compositions, for the treatment of allergic diseases and for the treatment of hyperplasias and malignancies, comprising as an active ingredient the above mentioned chimeric protein and a conventional adjuvant product.

[0024] The present invention further relates to the method for the preparation of these pharmaceutical compositions comprising genetically fused Fc region of the mouse IgE molecule to PE₄₀ and adding, if needed, a conventional adjuvant product. The pharmaceutical compositions according to the present invention may be in any suitable form for injection, for toppical application, or for oral administration.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The Fc-PE chimeric protein according to the present invention has a number of advantages over the existing known drugs.:

[0026] 1. Specificity: Fc-PE is highly specific, affecting the cells (mast cells and basophils) responsible for the release of allergic mediators. As it prevents the allergic attack, it can be of great value as a prophylactic treatment.

[0027] 2. Toxicity: As it acts on affector cells and not on it's target organs, Fc-PE is expected to have little, if any, side effects. Moreover, as the receptor is not expressed on stem cells, no damage to bone marrow and immunosupression are anticipated. Re-institution of a normal physiological state is expected to occur within several weeks after the end of the treatment.

[0028] 3. Duration of the effect: Because maturation of mast cells takes several weeks, the effect of Fc-PE is predicated to be long-standing, eliminating the need for frequent administration. Moreover, as in vitro studies indicate that reduction of 80% in cellular protein systhesis is observed in less than 4 hours, induction time of Fc-PE is expected to be relatively short, enabling it's usage in acute phase allergic reactions.

[0029] Fcε-PE can also be valuable in the treatment of hyperplasias and malignancies of mast cells and basophils, like systemic mastocytosis (in both benign and malignant forms) and basophilic leukemia. Chemotherapy is not appropriate for patients with benign mastocytosis due to severe side effects. On the other hand, there is no good clinical protocol for the treatment of the malignant diseases. Fcε-PE chimeric protein, being highly potent and selective can be used for both benign and malignant conditions involving cells expressing the FcεRI receptors.

[0030] The following experimental results indicate that the Fc_(2′-3-PE)40chimeric protein according to the present invention is a promising candidate for effective and selective allergy therapy.

[0031] The present invention provides a FCε-PE chimeric cytotoxin protein for the targered elimination of FcεRI expressing cells, useful especially for the therapy of allergic responses such as asthma, allergic rhinitis, food allergies, atopic dermatitis, and anaphylaxis.

[0032] The said invention will be further described in detail by the following experiments. These experiments do not intend to limit the scope of the invention but to demonstrate and clarify it only.

[0033] 1. Construction of Fcε-PE₄₀ chimeric proteins.

[0034] For the targeting moiety of the chimeric proteins fragments of the mouse IgE constant region (Fcε) are used as it binds both to human and to mouse high affinity IgE receptors (Conrad, D. H., Wingard, J. R., and Ishizaka, T. 1983 The interaction of human and rodent IgE with the human basophil IgE receptor. J. Immunol. 130, 327.).

[0035] We used a sequence corresponding to a.a. 301-437, containing the COOH terminus of domain 2 and the entire domain 3(C₂′-C₃). We used also a sequence corresponding to a.a. 225-552, containing the whole C₂-C₄domains. The cDNA for these fragments was obtained by RT-PCR, using RNA isolated from mouse B cells which were isotopically switched to secrete IgE and a specific set of primers. B cells obtained from the spleen of a 6-week-old BALB/C mouse were separated by negative selection using anti-Thy1.2 and rabbit complement. Cells were incubated at 2×10⁶ cells/ml in the presence of Lipopolysaccharide (LPS, 10 μg/ml) and IL₄ (500 u/ml) for 5 days to induce isotypic switching for IgE production. After 5 days, total cellular RNA was isolated (RNAzol TM B isolation kit produced by BIOTECK Laboratories, Houston, USA.). Total RNA (2.5 μg) was then reverse transcribed into first strand cDNA, using the reverse transcription System (Promega, USA) under conditions, recomended by the manfacturer. The cDNA was diluted to a total volume of 1 ml with TE buffer (10 mM Tris-HCL, pH 7.6, 1 mM EDTA) and stored at 4° C. until used.

[0036] Fcε fragmants were generated by PCR, using cDNA and a pair of synthetic oligonucleotide primers 5′-GCG GAT CCC ATA TGG AGC AAT GGA TGT CGT-3′ (sense, starting from nucleotide 406, according to gene bank sequence J00476) and 5′-GCG GAT CCC ATA TGT GGG GTC TTG GTG ATG GAA C-3′ (antisense, starting from nucleotide 813) for the Fcε_(2′-3) sequence and 5′-GCG GAT CCC ATA TGC GAC CTG TCA ACA TCA CTG-3′ (sense, starting from nucleotide 175) and 5′-GCG GAT CCC ATA TGG GAG GGA CGG AGG GAG G-3′(antisense, starting from nucleotide 1167) for the Fcε₂-₄ sequence.

[0037] Synthetic oligonucleotides were synthesized on an Applied Biosystems DNA synthesizer and purified on oligonucleotide purification cartridges. The vent polymerase enzyme (Biolabs) was used for amplification. The reaction mixture was incubated in a DNA thermal cycler (MJ Research, Inc, USA.) for 33 cycles. Each cycle consisted of 1 min. at 95° C., 1 min. at the annealing temperature and 2 min. at 72° C. The MgSO₄ concentration and the annealing temperature used for each primer pair were: 2.5 mM and 61° C. for Fc_(2′-3′), 2 mM and 57° C. for Fc₂₋₄.

[0038] The pHL 906 plasmid, which encodes IL₂-PE₄₀, was described previously (Fishman, A., Bar-Kana, Y., Steinberger, I., and Lorberboum-Galski, H. 1994. Increased cytotoxicity of IL2-PE chimeric proteins containing targeting signal for lysosomal membranes. Biochem. 33, 6235.). The pHL906 plasmid was cut with Ndel, obtaining the larger fragment of 3596 bp. The above Fcε fragment was inserted into the Ndel site of pHL906. The resulting plasmids, pAF2302 and pAF2415, coding for the C₂′-C₃ and C₂-C₄ fragments respectivly, each fused 5′ to PE₄₀, were characterized by restriction and sequence analysis (results not shown). Escherichia coli strain HB101 was used for transformation and preparation of the plasmids.

[0039] 2. Expression and partial purification of the chimeric proteins.

[0040] The newly designed chimeric protein, Fcε-PE₄₀ encoded by plasmid pAF2302 was expressed in E. coli strain BL21(lambda-DE3) which carries a T7 RNA polymerase gene in a lysogenic and inducible form. Induction was performed at O.D.₆₀₀0.5 or 180 min. in the presence of isopropyl β-D-thiogalactoside (IPTG, 1 mM final concentration). A pellet expressing cells was suspended in TE buffer (50 mM Tris pH 8.0, 1 mM EDTA) containing 0.2 mg/ml lysosyme, sonicated (three 30s bursts) and centrifuged at 30,000Xg for 30 min. The supernatant (soluble fraction) was removed and kept for analysis. The pellet was denatured in extraction buffer (6 M guanidine-hydrochloride, 0.1 M Tris pH 8.6, 1 mM EDTA, 0.05 M NaCl and 10 mM DTT) and stirred for 30 min. at 4° C. The suspention was cleared by centrifugation at 30,000Xg for 15 min. and the pellet discarded. The supernatant was; then dialysed against 0.1 M Tris (pH 8.0), 1 mM EDTA, 0.25 mM NaCl and 0.25 mM L-Arginine for 16 h. The dialysate was centrifuged at 15,0000Xg for 15 min. and the resultant supernatant (insoluble fraction, guanidine-hydrochiloride treated) was used as a source of the chimeric proteins. Proteins were characterized by gel electrophoresis (FIG. 2). The protein profile of whole cell extracts revealed the high expression level of the chimeric protein.

[0041] The protein was further characterized by Western blot analysis using antibodies against PE (FIG. 3A) and against IgE (Serotec, England) (FIG. 3B). The electrophoresed samples were transfered onto nitrocellulose and immunoblotted as described (Lorberboum-Galski, H., Fitzgerald, D. J., Chaudhary, V., Ashya, S., and Pastan, I. 1988. Cytotoxic activity of an interleukin 2 —Pseudomonas exotoxin chimeric protein produced in Escherichia coli. Proc. Natl. Acad. Sci. USA 85, 1992.). A Vectastain ABC Kit (Vector Laboratories, USA) was used according to the manufacturer's instructions. The chimera reacted with both antibodies, thus confirming the cloning and production of in-frame full-length chimeric protein.

[0042] Subcellular fractionation of expressing cells revealed that the insoluble fraction (inclusion bodies) was paticularly rich with chimeric protein (FIG. 2). This fraction was therefore used as the source of the chimeric protein.

[0043] The ADP-ribosylation activity of tested samples was measured using wheat germ extracts enriched in elongation factor 2 as substrate, as described previously, and revealed that the novel chimeric protein was enzymatically active (results not shown).

[0044] 3. Effect of Fc_(2′-3)-PE₄₀ chimeric protein on mouse mast cell lines.

[0045] The cytotoxic effect of the chimeric protein was tested on various mouse mast cell lines known to express the FcεRI receptor. The cytotoxic activity of the chimeric protein was evaluated by inhibition of protein synthesis, as measured by [³H] Leucine incorporation. Various concentrations of the chimeric protein, diluted with 0.25% bovine serum albumin in phosphate-buffered saline, were added to 2×10⁴ cells/0.2 ml seeded in 96-well plates for 20 h., followed by an 8 h pulse with 2 μCi of [³H]-Leucine. The results are expressed as a percentage of the control experiments in which the cells were not exposed to the chimeric protein. All assays were carried out in triplicate in three separate experiments.

[0046] Three target cell lines expressing the FcεRI receptor were used: MC-9, a mast cell line originating in mouse fetal liver and dependent on IL₃ for growth, C57, an IL₃ independent mast cell line originating in mouse bone marrow; and the Abelson-virus transformed mast cell line originating in mouse midgestation embryonic placenta. Fcε-PE₄₀ was found to be cytotoxic in a dose-dependent manner to all the cell lines tested (FIG. 4). The MC-9 and C57 lines were extremely sensitive to the chimeric toxin, with an ID₅₀ of 50-75 ng/ml and 100-125 ng/ml, respectively. The Alelson cell line was much less sensitive (ID₅₀ of 1200-1500 ng/ml).

[0047] 4. Specificity of FCε-PE₄₀ response.

[0048] To verify the specificity of Fc_(2′-3)PE₄₀ activity, two control proteins, PE₄₀ and Fc_(2′-3)-PE_(40M), were generated and evaluated for their effect on target and non target cells. To construct Fc_(2′-3)-PE_(40M), the region coding for the 122 amino acids at the C-terminal of PE was exised with EcoRI and BamHI and replaced by a corresponding fragment carrying a deletion at amino acid 553.

[0049] PE₄₀, which has no intrinsic targeting capacity had, as expected, no effect on the target cell lines (FIG. 4). Fc_(2′-3)-PE_(40M) which possesses a Fc_(2′-3) moiety linked to a mutated, enzymatically inactive form PE₄₀, was also not cytotoxic to the target cells (FIG. 4).

[0050] In addition, it was possible to block the cytotoxic effect of Fc_(2′-3)-PE₄₀ against target cells by whole mouse IgE (40 μg/ml, FIG. 5A) or by a αPE polyclonal antibody (10 μg/ml, FIG. 5B).

[0051] The effect of Fc_(2′-3)-PE₄₀ was also tested on various mouse non-target cell lines (Table 1). All cell lines of hemopoetic origin were unaffected by the chimeric protein. Suprisingly, fibroblast and hematoma cell lines exhibited some sensitivity to chimeric toxin, although the ID₅₀ values were twenty-fold higher than those of the MC-9 cells (Table 1).

[0052] The above data demonstrates that the toxic effect of Fc_(2′-3-PE)40 on mast cell lines is due to a specific response mediated by the Fc_(2′-3) moiety which targets the cytotoxic part of the chimera (PE₄₀) into the cell.

[0053] 5. Effect of chimeric proteins on primary mast cells.

[0054] As it is likely that fresh murine mast cells react differently from established cell lines, we also tested primary mast cells obtained from normal mice for their sensitivity to Fc_(2′-3)-PE₄₀. When cultured in the presence of IL₃ for two weeks, mouse bone marrow differentiates into an almost pure population of cells with the morphology of immature mast cells, containing granules and expressing the FcεRI receptor.

[0055] BALB/C mice aged 4-6 weeks were sacrified and their bone marrow was aseptically flushed from femurs into 0.9% cold NaCl. The cell suspension was washed twice with 0.9% NaCl, centrifuged for 10 min. at 300Xg and finally resuspended in RPMI 1640 medium containing 10% heat inactivated fetal calf serum, 4 mM L-glutamine, 1 mM sodium piruvate, 0.1 mM nonessential amino acids, 5×10⁻⁵ M β-mercaptoethanol, 100 u/ml penicillin, 100 μg/ml streptomycin and 20 u/ml recombinant mouse IL₃. Cells were grown in tissue culture flasks at a density of 10⁶ cells/ml, at 37° C. in a 5% CO₂ humidified atmosphere for 2-3 weeks. The media were changed every 7 days. Recombinant IL₄ (10u/ml) was added starting from day 7 in culture.

[0056] To follow the degree of maturation, cells were mounted on slides, stained with acidic Toluidine Blue (pH 1.0) and examined microscopically under oil.

[0057] The effect of chimeric proteins was tested on bone marrow derived mast cells (BMMC) on the 16th day of cultures. As shown in FIG. 6, Fc_(2′-3)-PE₄₀ was cytotoxic to BMMC in a dose dependent manner, with an ID₅₀ of 125 ng/ml. At a high chimeric protein dose, there was nearly 100% inhibition of protein synthesis. None of the control proteins Fc_(2′-3)-PE_(40M) or PE₄₀ displayed cytotoxicity against BMMC (FIG. 6). Thus, primary mast cells respond towards the chimeric protein similarly to the established mast cell lines (FIGS. 4 and 6).

[0058] 6. Receptor specificity of Fc_(2′-3)-PE₄₀.

[0059] Aside from the high affinity FcεRI receptor, three other membrane surface structures were reported to bind IgE with low affinity′the low affinity FcεRII receptor, the εBP galactoside-binding protein (also termed MAC-2 or CBP35) and the FcγRII/III receptor. These structures appear on various cell types, mainly of hemopoethic origin, but also on fibroblasts (εBP). FcγRII/III and εBP appear on mast cell membranes in addition to FcεRI. As our aim was to target only mast cells, it was essential to prove that the chimeric protein does not recognize these structures and thus can not be internalized through them. Theoretically our chimeric protein does not fulfill the binding requirements of the low-affinity IgE binding structure FcεRII, εBP and FcγRII/III. FcεRII binds only disulfide linked ε-chain dimmers, while our protein lacks domain 4 which is essential for dimerization. εBP binds only glycosylated IgE; Fc_(2′-3)-PE₄₀ being produced in bacteria, is not glycosylated. FcγRII/III binds IgE-immunocomplexes but not free IgE. Nevertheless, the issue of receptor binding was challenged experimentally.

[0060] Experiments involving εBP and FcγRII/III were performed on C57 mast cells, known to express these receptors in addition to FcεRI. To test whether the chimeric protein can enter the cell via the FcγRII/III receptors, cells were preincubated with the 2.4G2 antibody (Pharmigen) (50 μg/m) prior to addition of the chimeric protein. This monoclonal antibody, which binds to the extracellular domains of both FcγRII and the FcγRIII receptors was shown to be a competitive inhibitor of IgE binding. As can be seen in FIG. 7A, there was no difference in the cellular response to Fc_(2′-3)-PE₄₀ between control cells and cells preincubated with the antibody.

[0061] We next examined whether εBP is involved in the cytotoxicity of Fc_(2′-3)-PE₄₀. As εBP is attached to membrane carbohydrate determinants, addition of lactose to the culture medium causes its dissociation from the cell surface. We found no difference in the cellular response to Fc_(2′-3)-PE₄₀ in the presence or absence of lactose (25mM, FIG. 7B).

[0062] Additional experiments in the presence of 2.4G2 antibody and lactose were performed on fibroblast cell lines that were found partially responsive to the chimeric protein (Table 1). Again, there was no difference in FC_(2′-3)-PE₄₀ cytotoxicity against treated and control cells (results not shown).

[0063] To test whether Fc_(2′-3)-PE₄₀ affects FcεRII-bearing cells, we used the 0.12A3 cell line, a mouse B cell hybridoma expressing the FcεRII receptor. The 0.12A3 cells were totally non responsive to Fc_(2′-3)-PE₄₀, even at high doses (>5000 ng/ml, FIG. 8A). As this line loses the receptor upon long term culture, the assay was followed by FACS analysis with the B3B4 antibody against the receptor (Pharmigin). The results showed that the receptor was expressed on 54% of the cells (results not shown).

[0064] An additional experiment was performed on fresh mouse B splenocytes preincubated for 16 h. with LPS (50 μg/ml) to stimulate expression of FcεRII. Fc_(2′-3)-PE₄₀ has no effect on these B splenocytes (FIG. 8B), although 69% of the cells expressed the receptor, as determined by FACS analysis.

[0065] Collectively, these results suggest that Fc_(2′-3)-PE₄₀ does not bind to the low affinity IgE-binding structures, namely FcεRII, FcγRII/III and εBP.

[0066] 7. Effect of Fc_(2′-3)-PE₄₀ on cellular degranulation.

[0067] Because of the possible clinical applicability of Fc_(2′-3)-PE₄₀, it was important to test whether treatment of mast cells with Fc_(2′-3)-PE₄₀ results in the release of allergic mediators triggered upon FcεRI binding by the chimetric protein.

[0068] C57 cells prelabelled overnight with [³H]-hydroxytryptamine (10 μci/ml) were washed, plated at 2×10⁵ cells/well in DMEM containing 10% FCS, in 96-well tissue culture plates and incubated with Fc_(2′-3)-PE₄₀ (10 μg/ml) at 37° C. At various time points, supernatants were separated and release of seretonin into the supernatant was measured. Unlabled cells were also incubated with Fc_(2′-3)-PE₄₀ and at the same time intervals were pulsed 1 hr with [³H] leucine to measure protein systhesis inhibition by chimeric toxin. There was no difference in supernatant [3H] seretonin content between Fc_(2′-3)-PE₄₀ treated and untreated cells at ½, 4 or 8 hr following chimeric protein addition (FIG. 9A). Inhibition of protein synthesis reached 80% at 4 h. and a value of 90% by 8 h. (FIG. 9B). These results suggest that Fc_(2′-3)-PE₄₀ does not cause release of allergic mediators during receptor binding or upon inhibition of protein synthesis.

[0069] 8.Electrophoretic characterization of Fcε-PE40

[0070] Western blot analysis of electrophoresed samples run under non-reducing conditions (omitting 2-mercaptoethanol from the sample buffer) revealed that the Fc2′-3-PE40 chimeric protein is predominantly present as a monomer (FIG. 10b). For native PAGE, 2-mercaptoethanol was omitted from the sample buffer and the samples were not heated. In addition, SDS was replaced with equivalent volumes of water in the gel, sample buffer and electrode running buffer. Under non-denaturing conditions the chimeric protein runs as a broad band (FIG. 10c). A single native system can not distinguish the effects of molecular weight, charge and conformation on protein electrophoretic mobilities. However, the proximity of the molecules in the band indicates that they can not differ much in these parameters.

[0071] 9. Internalization assay

[0072] In vitro activity of the chimeric protein is achieved only upon it's internalization. To rest whether the chimeric protein is internalysed, 5×10⁵ cells/3 ml were incubated for 1 hour with 20 μg of the chimeric protein at 37° C. After 3 washes with cold PBS the pellet was treated with 0.5 ml of acid solution (0.15M NaCl, 0.15M acetic acid (pH 3)) for 3 min on ice to remove membrane-bounded chimeric protein. The pH was then neutrilised by addition of 50% FCS following by three washed with RPMI/10% FCS. The cell pellet was lysed with 0.3 ml of RIPA lysis buffer (150 mM NaCl, 1 mM EDTA, 20 mM tris-HCl pH 7.4, 1 mM phenylmethylsulfonyl fluoride, 15% SDS, 1% deoxycholyc acid, 1% Nonidet P-40). Various samples were electrophoresed and immunoblotted using α-PE and the ECL detection system (Amersham). Western blot analysis revealed undoubtfully that Fc2′-3-PE40 chimeric protein is internalized into the target cells (FIG. 11).

[0073] 10. Effect of Fc_(2′-3)-PE₄₀ on cellular degranulation

[0074] C57 cells were incubated overnight with [³H]-Hydroxytryptamine (10 μci/ml) at 37° C. Cells were washed 3 times to remove free [3H]-Hydroxytryptamine, plated in Tyrod's buffer (10mM Hepes pH 7.4, 130 mM NaCl, 5 mM KCl, 5.6 mM Glucose, 0.5% BSA) at 2.5×10⁵ cells/0.5 ml in 24 well tissue culture plates and incubated with IgE (10 μg/ml) for 1 hour at 4° C. MgCl₂ and CaCl₂ were then added to the final concentration of 1 mM and 1.6 mM respectively, following by incubation with Dinitrophenyl-human serum albumin (DNP-HSA, 50 ng/ml) for 30 minutes or with the different concentrations of chimeric protein for various times at 37° C. Cell-free supernatants were collected by centrifugation and amount of [³H]-Hydroxytryptamine released was measured. No degranulation was observed with any concentration of chimeric protein tested (FIG. 12a). As a control, cells preincubated with IgE were exposed to DNP under the same conditions. The effect of triggering degranulation by DNP is clearly visible (FIG. 12a). Fc_(2′-3)-PE₄₀ did not cause any degranulation also at later stages of it's interaction with the target cell (FIG. 12b), while it inhibits protein synthesis by over 80% (FIG. 12c). Our results demonstrate that Fc_(2′-3)-PE₄₀_does not_trigger degr anulation at any stage during it's interaction with the cell. TABLE 1 Cytotoxicity of Fc_(2′-3)-PE₄₀ chimeric protein against various mouse cells Cell line Cell Origin ID₅₀ (ng/ml) TARGET MC-9 Mast cells  50-100 CELLS C57 Mast cells 100-125 BMMC Primary bone marrow-derived mast cells Abelson Transformed mast 1,200-1,500 cells NON- HEMO- L₁₀A B cell, >10,000 TARGET POETIC non-secreting CELLS X₁₆B B cell, >10,000 non-secreting UT B cell, >10,000 non-secreting PD1.1 T cell, immature >10,000 EL-4 T cell, mature >10,000 Erythro- >10,000 leukemia CONNECTIVE LTK Fibroblast 1900 TISSUE Hepatoma 1500

[0075]

1 8 1 1512 DNA Mouse CDS (1)..(1512) 1. The mouse IgE constant region (=F(Ce)) 2. Pseudomonas aeruginosa Endotoxin (PE40) 1 atg gag cag caa tgg atg tct gaa agc acc ttc acc tgc aag gtc acc 48 Met Glu Gln Gln Trp Met Ser Glu Ser Thr Phe Thr Cys Lys Val Thr 1 5 10 15 tcc caa ggc gta gac tat ttg gcc cac act cgg aga tgc cca gat cat 96 Ser Gln Gly Val Asp Tyr Leu Ala His Thr Arg Arg Cys Pro Asp His 20 25 30 gag cca gcc ggt gtg att acc tac ctg atc cca ccc agc ccc ctg gac 144 Glu Pro Ala Gly Val Ile Thr Tyr Leu Ile Pro Pro Ser Pro Leu Asp 35 40 45 ctg tat caa aac ggt gct ccc aag ctt acc tgt ctg gtg gtg gac ctg 192 Leu Tyr Gln Asn Gly Ala Pro Lys Leu Thr Cys Leu Val Val Asp Leu 50 55 60 gaa agc gag aag aat gtc aat gtg acg tgg aac caa gag aag aag act 240 Glu Ser Glu Lys Asn Val Asn Val Thr Trp Asn Gln Glu Lys Lys Thr 65 70 75 80 tca gtc tca gca tcc cag tgg tac act aag cac cac aat aac gcc aca 288 Ser Val Ser Ala Ser Gln Trp Tyr Thr Lys His His Asn Asn Ala Thr 85 90 95 act agt atc acc tcc atc ctg cct gta gtt gcc aag gac tgg att gaa 336 Thr Ser Ile Thr Ser Ile Leu Pro Val Val Ala Lys Asp Trp Ile Glu 100 105 110 ggc tac ggc tat cag tgc ata gtg gac cac cct gat ttt ccc aag ccc 384 Gly Tyr Gly Tyr Gln Cys Ile Val Asp His Pro Asp Phe Pro Lys Pro 115 120 125 att gtg cgt tcc atc acc aag acc cca cat atg gcc gaa gag ggc ggc 432 Ile Val Arg Ser Ile Thr Lys Thr Pro His Met Ala Glu Glu Gly Gly 130 135 140 agc ctg gcc gcg ctg acc gcg cac cag gct tgc cac ctg ccg ctg gag 480 Ser Leu Ala Ala Leu Thr Ala His Gln Ala Cys His Leu Pro Leu Glu 145 150 155 160 act ttc acc cgt cat cgc cag ccg cgc ggc tgg gaa caa ctg gag cag 528 Thr Phe Thr Arg His Arg Gln Pro Arg Gly Trp Glu Gln Leu Glu Gln 165 170 175 tgc ggc tat ccg gtg cag cgg ctg gtc gcc ctc tac ctg gcg gcg cgg 576 Cys Gly Tyr Pro Val Gln Arg Leu Val Ala Leu Tyr Leu Ala Ala Arg 180 185 190 ctg tcg tgg aac cag gtc gac cag gtg atc cgc aac gcc ctg gcc agc 624 Leu Ser Trp Asn Gln Val Asp Gln Val Ile Arg Asn Ala Leu Ala Ser 195 200 205 ccc ggc agc ggc ggc gac ctg ggc gaa gcg atc cgc gag cag ccg gag 672 Pro Gly Ser Gly Gly Asp Leu Gly Glu Ala Ile Arg Glu Gln Pro Glu 210 215 220 cag gcc cgt ctg gcc ctg acc ctg gcc gcc gcc gag agc gag cgc ttc 720 Gln Ala Arg Leu Ala Leu Thr Leu Ala Ala Ala Glu Ser Glu Arg Phe 225 230 235 240 gtc cgg cag ggc acc ggc aac gac gag gcc ggc gcg gcc aac gcc gac 768 Val Arg Gln Gly Thr Gly Asn Asp Glu Ala Gly Ala Ala Asn Ala Asp 245 250 255 gtg gtg agc ctg acc tgc ccg gtc gcc gcc ggt gaa tgc gcg ggc ccg 816 Val Val Ser Leu Thr Cys Pro Val Ala Ala Gly Glu Cys Ala Gly Pro 260 265 270 gcg gac agc ggc gac gcc ctg ctg gag cgc aac tat ccc act ggc gcg 864 Ala Asp Ser Gly Asp Ala Leu Leu Glu Arg Asn Tyr Pro Thr Gly Ala 275 280 285 gag ttc ctc ggc gac ggc ggc gac gtc agc ttc agc acc cgc ggc acg 912 Glu Phe Leu Gly Asp Gly Gly Asp Val Ser Phe Ser Thr Arg Gly Thr 290 295 300 cag aac tgg acg gtg gag cgg ctg ctc cag gcg cac cgc caa ctg gag 960 Gln Asn Trp Thr Val Glu Arg Leu Leu Gln Ala His Arg Gln Leu Glu 305 310 315 320 gag cgc ggc tat gtg ttc gtc ggc tac cac ggc acc ttc ctc gaa gcg 1008 Glu Arg Gly Tyr Val Phe Val Gly Tyr His Gly Thr Phe Leu Glu Ala 325 330 335 gcg caa agc atc gtc ttc ggc ggg gtg cgc gcg cgc agc cag gac ctc 1056 Ala Gln Ser Ile Val Phe Gly Gly Val Arg Ala Arg Ser Gln Asp Leu 340 345 350 gac gcg atc tgg cgc ggt ttc tat atc gcc ggc gat ccg gcg ctg gcc 1104 Asp Ala Ile Trp Arg Gly Phe Tyr Ile Ala Gly Asp Pro Ala Leu Ala 355 360 365 tac ggc tac gcc cag gac cag gaa ccc gac gca cgc ggc cgg atc cgc 1152 Tyr Gly Tyr Ala Gln Asp Gln Glu Pro Asp Ala Arg Gly Arg Ile Arg 370 375 380 aac ggt gcc ctg ctg cgg gtc tat gtc ccg cgc tcg agc ctg ccg ggc 1200 Asn Gly Ala Leu Leu Arg Val Tyr Val Pro Arg Ser Ser Leu Pro Gly 385 390 395 400 ttc tac cgc acc agc ctg acc ctg gcc gcg ccg gag gcg gcg ggc gag 1248 Phe Tyr Arg Thr Ser Leu Thr Leu Ala Ala Pro Glu Ala Ala Gly Glu 405 410 415 gtc gaa cgg ctg atc ggc cat ccg ctg ccg ctg cgc ctg gac gcc atc 1296 Val Glu Arg Leu Ile Gly His Pro Leu Pro Leu Arg Leu Asp Ala Ile 420 425 430 acc ggc ccc gag gag gaa ggc ggg cgc ctg gag acc att ctc ggc tgg 1344 Thr Gly Pro Glu Glu Glu Gly Gly Arg Leu Glu Thr Ile Leu Gly Trp 435 440 445 ccg ctg gcc gag cgc acc gtg gtg att ccc tcg gcg atc ccc acc gac 1392 Pro Leu Ala Glu Arg Thr Val Val Ile Pro Ser Ala Ile Pro Thr Asp 450 455 460 ccg cgc aac gtc ggc ggc gac ctc gac ccg tcc agc atc ccc gac aag 1440 Pro Arg Asn Val Gly Gly Asp Leu Asp Pro Ser Ser Ile Pro Asp Lys 465 470 475 480 gaa cag gcg atc agc gcc ctg ccg gac tac gcc agc cag ccc ggc aaa 1488 Glu Gln Ala Ile Ser Ala Leu Pro Asp Tyr Ala Ser Gln Pro Gly Lys 485 490 495 ccg ccg cgc gag gac ctg aag taa 1512 Pro Pro Arg Glu Asp Leu Lys 500 2 503 PRT Mouse 2 Met Glu Gln Gln Trp Met Ser Glu Ser Thr Phe Thr Cys Lys Val Thr 1 5 10 15 Ser Gln Gly Val Asp Tyr Leu Ala His Thr Arg Arg Cys Pro Asp His 20 25 30 Glu Pro Ala Gly Val Ile Thr Tyr Leu Ile Pro Pro Ser Pro Leu Asp 35 40 45 Leu Tyr Gln Asn Gly Ala Pro Lys Leu Thr Cys Leu Val Val Asp Leu 50 55 60 Glu Ser Glu Lys Asn Val Asn Val Thr Trp Asn Gln Glu Lys Lys Thr 65 70 75 80 Ser Val Ser Ala Ser Gln Trp Tyr Thr Lys His His Asn Asn Ala Thr 85 90 95 Thr Ser Ile Thr Ser Ile Leu Pro Val Val Ala Lys Asp Trp Ile Glu 100 105 110 Gly Tyr Gly Tyr Gln Cys Ile Val Asp His Pro Asp Phe Pro Lys Pro 115 120 125 Ile Val Arg Ser Ile Thr Lys Thr Pro His Met Ala Glu Glu Gly Gly 130 135 140 Ser Leu Ala Ala Leu Thr Ala His Gln Ala Cys His Leu Pro Leu Glu 145 150 155 160 Thr Phe Thr Arg His Arg Gln Pro Arg Gly Trp Glu Gln Leu Glu Gln 165 170 175 Cys Gly Tyr Pro Val Gln Arg Leu Val Ala Leu Tyr Leu Ala Ala Arg 180 185 190 Leu Ser Trp Asn Gln Val Asp Gln Val Ile Arg Asn Ala Leu Ala Ser 195 200 205 Pro Gly Ser Gly Gly Asp Leu Gly Glu Ala Ile Arg Glu Gln Pro Glu 210 215 220 Gln Ala Arg Leu Ala Leu Thr Leu Ala Ala Ala Glu Ser Glu Arg Phe 225 230 235 240 Val Arg Gln Gly Thr Gly Asn Asp Glu Ala Gly Ala Ala Asn Ala Asp 245 250 255 Val Val Ser Leu Thr Cys Pro Val Ala Ala Gly Glu Cys Ala Gly Pro 260 265 270 Ala Asp Ser Gly Asp Ala Leu Leu Glu Arg Asn Tyr Pro Thr Gly Ala 275 280 285 Glu Phe Leu Gly Asp Gly Gly Asp Val Ser Phe Ser Thr Arg Gly Thr 290 295 300 Gln Asn Trp Thr Val Glu Arg Leu Leu Gln Ala His Arg Gln Leu Glu 305 310 315 320 Glu Arg Gly Tyr Val Phe Val Gly Tyr His Gly Thr Phe Leu Glu Ala 325 330 335 Ala Gln Ser Ile Val Phe Gly Gly Val Arg Ala Arg Ser Gln Asp Leu 340 345 350 Asp Ala Ile Trp Arg Gly Phe Tyr Ile Ala Gly Asp Pro Ala Leu Ala 355 360 365 Tyr Gly Tyr Ala Gln Asp Gln Glu Pro Asp Ala Arg Gly Arg Ile Arg 370 375 380 Asn Gly Ala Leu Leu Arg Val Tyr Val Pro Arg Ser Ser Leu Pro Gly 385 390 395 400 Phe Tyr Arg Thr Ser Leu Thr Leu Ala Ala Pro Glu Ala Ala Gly Glu 405 410 415 Val Glu Arg Leu Ile Gly His Pro Leu Pro Leu Arg Leu Asp Ala Ile 420 425 430 Thr Gly Pro Glu Glu Glu Gly Gly Arg Leu Glu Thr Ile Leu Gly Trp 435 440 445 Pro Leu Ala Glu Arg Thr Val Val Ile Pro Ser Ala Ile Pro Thr Asp 450 455 460 Pro Arg Asn Val Gly Gly Asp Leu Asp Pro Ser Ser Ile Pro Asp Lys 465 470 475 480 Glu Gln Ala Ile Ser Ala Leu Pro Asp Tyr Ala Ser Gln Pro Gly Lys 485 490 495 Pro Pro Arg Glu Asp Leu Lys 500 3 2031 DNA Pseudomonas aeruginosa CDS (1)..(2031) 1. The mouse IgE constant region (=F(Ce)) 2. Pseudomonas aeruginosa Endotoxin (PE40) 3 atg cga cct gtc aac atc act gag ccc acc ttg gag cta ctc cat tca 48 Met Arg Pro Val Asn Ile Thr Glu Pro Thr Leu Glu Leu Leu His Ser 1 5 10 15 tcc tgc gac ccc aat gca ttc cac tcc acc atc cag ctg tac tgc ttc 96 Ser Cys Asp Pro Asn Ala Phe His Ser Thr Ile Gln Leu Tyr Cys Phe 20 25 30 att tat ggc cac atc cta aat gat gtc tct gtc agc tgg cta atg gac 144 Ile Tyr Gly His Ile Leu Asn Asp Val Ser Val Ser Trp Leu Met Asp 35 40 45 gat cgg gag ata act gat aca ctt gca caa act gtt cta atc aag gag 192 Asp Arg Glu Ile Thr Asp Thr Leu Ala Gln Thr Val Leu Ile Lys Glu 50 55 60 gaa ggc aaa cta gcc tct acc tgc agt aaa ctc aac atc act gag cag 240 Glu Gly Lys Leu Ala Ser Thr Cys Ser Lys Leu Asn Ile Thr Glu Gln 65 70 75 80 caa tgg atg tct gaa agc acc ttc acc tgc aag gtc acc tcc caa ggc 288 Gln Trp Met Ser Glu Ser Thr Phe Thr Cys Lys Val Thr Ser Gln Gly 85 90 95 gta gac tat ttg gcc cac act cgg aga tgc cca gat cat gag cca cgg 336 Val Asp Tyr Leu Ala His Thr Arg Arg Cys Pro Asp His Glu Pro Arg 100 105 110 ggt gtg att acc tac ctg atc cca ccc agc ccc ctg gac ctg tat caa 384 Gly Val Ile Thr Tyr Leu Ile Pro Pro Ser Pro Leu Asp Leu Tyr Gln 115 120 125 aac ggt gct ccc aag ctt acc tgt ctg gtg gtg gac ctg gaa agc gag 432 Asn Gly Ala Pro Lys Leu Thr Cys Leu Val Val Asp Leu Glu Ser Glu 130 135 140 aag aat gtc aat gtg acg tgg aac caa gag aag aag act tca gtc tca 480 Lys Asn Val Asn Val Thr Trp Asn Gln Glu Lys Lys Thr Ser Val Ser 145 150 155 160 gca tcc cag tgg tac act aag cac cac aat aac ggc aca act agt atc 528 Ala Ser Gln Trp Tyr Thr Lys His His Asn Asn Gly Thr Thr Ser Ile 165 170 175 acc tcc atc ctg cct gta gtt gcc aag gac tgg att gaa ggc tac ggc 576 Thr Ser Ile Leu Pro Val Val Ala Lys Asp Trp Ile Glu Gly Tyr Gly 180 185 190 tat cag tgc ata gtg gac cac cct gat ttt ccc aag ccc att gtg cgt 624 Tyr Gln Cys Ile Val Asp His Pro Asp Phe Pro Lys Pro Ile Val Arg 195 200 205 tcc atc acc aag acc cca ggc cag cgc tca gcc ccc gag gta tat gtg 672 Ser Ile Thr Lys Thr Pro Gly Gln Arg Ser Ala Pro Glu Val Tyr Val 210 215 220 ttc cca cca cca gag gag gag agc gag gac aaa cgc aca ctc acc tgt 720 Phe Pro Pro Pro Glu Glu Glu Ser Glu Asp Lys Arg Thr Leu Thr Cys 225 230 235 240 ttg atc cag aac ttc ttc cct gag gat atc tct gtg cag tgg ctg ggg 768 Leu Ile Gln Asn Phe Phe Pro Glu Asp Ile Ser Val Gln Trp Leu Gly 245 250 255 gat ggc aaa ctg atc tca aac agc cag cac agt acc aca aca ccc ctg 816 Asp Gly Lys Leu Ile Ser Asn Ser Gln His Ser Thr Thr Thr Pro Leu 260 265 270 aaa tcc aat ggc tcc aat caa ggc ttc ttc atc ttc agt cgc cta gag 864 Lys Ser Asn Gly Ser Asn Gln Gly Phe Phe Ile Phe Ser Arg Leu Glu 275 280 285 gtc gcc aag aca ctc tgg aca cag aga aaa cag ttc acc tgc caa gtg 912 Val Ala Lys Thr Leu Trp Thr Gln Arg Lys Gln Phe Thr Cys Gln Val 290 295 300 atc cat gag gca ctt cag cat atg gcc gaa gag ggc ggc agc ctg gcc 960 Ile His Glu Ala Leu Gln His Met Ala Glu Glu Gly Gly Ser Leu Ala 305 310 315 320 gcg ctg acc gcg cac cag gct tgc cac ctg ccg ctg gag act ttc acc 1008 Ala Leu Thr Ala His Gln Ala Cys His Leu Pro Leu Glu Thr Phe Thr 325 330 335 cgt cat cgc cag ccg cgc ggc tgg gaa caa ctg gag cag tgc ggc tat 1056 Arg His Arg Gln Pro Arg Gly Trp Glu Gln Leu Glu Gln Cys Gly Tyr 340 345 350 ccg gtg cag cgg ctg gtc gcc ctc tac ctg gcg gcg cgg ctg tcg tgg 1104 Pro Val Gln Arg Leu Val Ala Leu Tyr Leu Ala Ala Arg Leu Ser Trp 355 360 365 aac cag gtc gac cag gtg atc cgc aac gcc ctg gcc agc ccc ggc agc 1152 Asn Gln Val Asp Gln Val Ile Arg Asn Ala Leu Ala Ser Pro Gly Ser 370 375 380 ggc ggc agc ctg ggc gaa gcg atc cgc gag cag ccg gag cag gcc cgt 1200 Gly Gly Ser Leu Gly Glu Ala Ile Arg Glu Gln Pro Glu Gln Ala Arg 385 390 395 400 ctg gcc ctg acc ctg gcc gcc gcc gag agc gag cgc ttc gtc cgg cag 1248 Leu Ala Leu Thr Leu Ala Ala Ala Glu Ser Glu Arg Phe Val Arg Gln 405 410 415 ggc acc ggc aac gac gag gcc ggc gcg gcc aac gcc gac gtg gtg agc 1296 Gly Thr Gly Asn Asp Glu Ala Gly Ala Ala Asn Ala Asp Val Val Ser 420 425 430 ctg acc tgc ccg gtc gcc gcc ggt gaa tgc gcg ggc ccg gcg gac agc 1344 Leu Thr Cys Pro Val Ala Ala Gly Glu Cys Ala Gly Pro Ala Asp Ser 435 440 445 ggc gac gcc ctg ctg gag cgc aac tat ccc act ggc gcg gag ttc ctc 1392 Gly Asp Ala Leu Leu Glu Arg Asn Tyr Pro Thr Gly Ala Glu Phe Leu 450 455 460 ggc gac ggc ggc gac gtc agc ttc agc acc cgc ggc acg cag aac tgg 1440 Gly Asp Gly Gly Asp Val Ser Phe Ser Thr Arg Gly Thr Gln Asn Trp 465 470 475 480 acg gtg gag cgg ctg ctc cag gcg cac cgc caa ctg gag gag cgc ggc 1488 Thr Val Glu Arg Leu Leu Gln Ala His Arg Gln Leu Glu Glu Arg Gly 485 490 495 tat gtg ttc gtc ggc tac cac ggc acc ttc ctc gaa gcg gcg caa agc 1536 Tyr Val Phe Val Gly Tyr His Gly Thr Phe Leu Glu Ala Ala Gln Ser 500 505 510 atc gtc ttc ggc ggg gtg cgc gcg cgc agc cag gac ctc gac gcg atc 1584 Ile Val Phe Gly Gly Val Arg Ala Arg Ser Gln Asp Leu Asp Ala Ile 515 520 525 tgg cgc ggt ttc tat atc gcc ggc gat ccg gcg ctg gcc tac ggc tac 1632 Trp Arg Gly Phe Tyr Ile Ala Gly Asp Pro Ala Leu Ala Tyr Gly Tyr 530 535 540 gcc cag gac cag gaa ccc gac gca cgc ggc cgg atc cgc aac ggt gcc 1680 Ala Gln Asp Gln Glu Pro Asp Ala Arg Gly Arg Ile Arg Asn Gly Ala 545 550 555 560 ctg ctg cgg gtc tat gtg ccg cgc tcg agc ctg ccg ggc ttc tac cgc 1728 Leu Leu Arg Val Tyr Val Pro Arg Ser Ser Leu Pro Gly Phe Tyr Arg 565 570 575 acc agc ctg acc ctg gcc gcg ccg gag gcg gcg ggc gag gtc gaa cgg 1776 Thr Ser Leu Thr Leu Ala Ala Pro Glu Ala Ala Gly Glu Val Glu Arg 580 585 590 ctg atc ggc cat ccg ctg ccg ctg cgc ctg gac gcc atc acc ggc ccc 1824 Leu Ile Gly His Pro Leu Pro Leu Arg Leu Asp Ala Ile Thr Gly Pro 595 600 605 gag gag gaa ggc ggg cgc ctg gag acc att ctc ggc tgg ccg ctg gcc 1872 Glu Glu Glu Gly Gly Arg Leu Glu Thr Ile Leu Gly Trp Pro Leu Ala 610 615 620 gag cgc acc gtg gtg att ccc tcg gcg atc ccc acc gac ccg cgc aac 1920 Glu Arg Thr Val Val Ile Pro Ser Ala Ile Pro Thr Asp Pro Arg Asn 625 630 635 640 gtc ggc ggc gac ctc gac ccg tcc agc atc ccc gac aag gaa cag gcg 1968 Val Gly Gly Asp Leu Asp Pro Ser Ser Ile Pro Asp Lys Glu Gln Ala 645 650 655 atc agc gcc ctg ccg gac tac gcc agc cag ccc ggc aaa ccg ccg cgc 2016 Ile Ser Ala Leu Pro Asp Tyr Ala Ser Gln Pro Gly Lys Pro Pro Arg 660 665 670 gag gac ctg aag taa 2031 Glu Asp Leu Lys 675 4 676 PRT Pseudomonas aeruginosa 4 Met Arg Pro Val Asn Ile Thr Glu Pro Thr Leu Glu Leu Leu His Ser 1 5 10 15 Ser Cys Asp Pro Asn Ala Phe His Ser Thr Ile Gln Leu Tyr Cys Phe 20 25 30 Ile Tyr Gly His Ile Leu Asn Asp Val Ser Val Ser Trp Leu Met Asp 35 40 45 Asp Arg Glu Ile Thr Asp Thr Leu Ala Gln Thr Val Leu Ile Lys Glu 50 55 60 Glu Gly Lys Leu Ala Ser Thr Cys Ser Lys Leu Asn Ile Thr Glu Gln 65 70 75 80 Gln Trp Met Ser Glu Ser Thr Phe Thr Cys Lys Val Thr Ser Gln Gly 85 90 95 Val Asp Tyr Leu Ala His Thr Arg Arg Cys Pro Asp His Glu Pro Arg 100 105 110 Gly Val Ile Thr Tyr Leu Ile Pro Pro Ser Pro Leu Asp Leu Tyr Gln 115 120 125 Asn Gly Ala Pro Lys Leu Thr Cys Leu Val Val Asp Leu Glu Ser Glu 130 135 140 Lys Asn Val Asn Val Thr Trp Asn Gln Glu Lys Lys Thr Ser Val Ser 145 150 155 160 Ala Ser Gln Trp Tyr Thr Lys His His Asn Asn Gly Thr Thr Ser Ile 165 170 175 Thr Ser Ile Leu Pro Val Val Ala Lys Asp Trp Ile Glu Gly Tyr Gly 180 185 190 Tyr Gln Cys Ile Val Asp His Pro Asp Phe Pro Lys Pro Ile Val Arg 195 200 205 Ser Ile Thr Lys Thr Pro Gly Gln Arg Ser Ala Pro Glu Val Tyr Val 210 215 220 Phe Pro Pro Pro Glu Glu Glu Ser Glu Asp Lys Arg Thr Leu Thr Cys 225 230 235 240 Leu Ile Gln Asn Phe Phe Pro Glu Asp Ile Ser Val Gln Trp Leu Gly 245 250 255 Asp Gly Lys Leu Ile Ser Asn Ser Gln His Ser Thr Thr Thr Pro Leu 260 265 270 Lys Ser Asn Gly Ser Asn Gln Gly Phe Phe Ile Phe Ser Arg Leu Glu 275 280 285 Val Ala Lys Thr Leu Trp Thr Gln Arg Lys Gln Phe Thr Cys Gln Val 290 295 300 Ile His Glu Ala Leu Gln His Met Ala Glu Glu Gly Gly Ser Leu Ala 305 310 315 320 Ala Leu Thr Ala His Gln Ala Cys His Leu Pro Leu Glu Thr Phe Thr 325 330 335 Arg His Arg Gln Pro Arg Gly Trp Glu Gln Leu Glu Gln Cys Gly Tyr 340 345 350 Pro Val Gln Arg Leu Val Ala Leu Tyr Leu Ala Ala Arg Leu Ser Trp 355 360 365 Asn Gln Val Asp Gln Val Ile Arg Asn Ala Leu Ala Ser Pro Gly Ser 370 375 380 Gly Gly Ser Leu Gly Glu Ala Ile Arg Glu Gln Pro Glu Gln Ala Arg 385 390 395 400 Leu Ala Leu Thr Leu Ala Ala Ala Glu Ser Glu Arg Phe Val Arg Gln 405 410 415 Gly Thr Gly Asn Asp Glu Ala Gly Ala Ala Asn Ala Asp Val Val Ser 420 425 430 Leu Thr Cys Pro Val Ala Ala Gly Glu Cys Ala Gly Pro Ala Asp Ser 435 440 445 Gly Asp Ala Leu Leu Glu Arg Asn Tyr Pro Thr Gly Ala Glu Phe Leu 450 455 460 Gly Asp Gly Gly Asp Val Ser Phe Ser Thr Arg Gly Thr Gln Asn Trp 465 470 475 480 Thr Val Glu Arg Leu Leu Gln Ala His Arg Gln Leu Glu Glu Arg Gly 485 490 495 Tyr Val Phe Val Gly Tyr His Gly Thr Phe Leu Glu Ala Ala Gln Ser 500 505 510 Ile Val Phe Gly Gly Val Arg Ala Arg Ser Gln Asp Leu Asp Ala Ile 515 520 525 Trp Arg Gly Phe Tyr Ile Ala Gly Asp Pro Ala Leu Ala Tyr Gly Tyr 530 535 540 Ala Gln Asp Gln Glu Pro Asp Ala Arg Gly Arg Ile Arg Asn Gly Ala 545 550 555 560 Leu Leu Arg Val Tyr Val Pro Arg Ser Ser Leu Pro Gly Phe Tyr Arg 565 570 575 Thr Ser Leu Thr Leu Ala Ala Pro Glu Ala Ala Gly Glu Val Glu Arg 580 585 590 Leu Ile Gly His Pro Leu Pro Leu Arg Leu Asp Ala Ile Thr Gly Pro 595 600 605 Glu Glu Glu Gly Gly Arg Leu Glu Thr Ile Leu Gly Trp Pro Leu Ala 610 615 620 Glu Arg Thr Val Val Ile Pro Ser Ala Ile Pro Thr Asp Pro Arg Asn 625 630 635 640 Val Gly Gly Asp Leu Asp Pro Ser Ser Ile Pro Asp Lys Glu Gln Ala 645 650 655 Ile Ser Ala Leu Pro Asp Tyr Ala Ser Gln Pro Gly Lys Pro Pro Arg 660 665 670 Glu Asp Leu Lys 675 5 30 DNA Synthetic Oligonucleotide 5 gcggatccca tatggagcaa tggatgtcgt 30 6 33 DNA Synthetic Oligonucleotide 6 gcggatccca tatgtggggt cttggtgatg gaa 33 7 33 DNA Synthetic Oligonucleotide 7 gcggatccca tatgcgacct gtcaacatca ctg 33 8 30 DNA Synthetic Oligonucleotide 8 gcggatccca tatgggaggg acggagggag 30 

1. A chimeric protein for the therapy of allergic responses by the way of targeted elimination of FcεRI expressing cells wherein the said chimeric protein is comprised of a cell targeting moiety for the FcεRI expressing cells and a cell killing moiety.
 2. A chimeric protein according to claim 1 wherein the killing moiety is the bacterial toxin Pseudomonas exotoxin (PE).
 3. A chimeric protein according to claim 1 wherein the cell targeting moiety is the Fc region of the mouse IgE molecule.
 4. A chimeric protein according to claim 1 wherein the cell targeting and cell killing moieties are genetically fused.
 5. A chimeric protein according to claim 1 wherein a sequence encoding amino acids 225-552 of the Fc region of the mouse IgE molecule is genetically fused to PE₄₀, a truncated form of PE lacking the cell binding domain.
 6. A chimeric protein according to claim 1 wherein a sequence encoding amino acids 301-437 of the Fc region of the mouse IgE molecule is genetically fused to PE₄₀, a truncated form of PE lacking the cell binding domain.
 7. A chimeric protein as defined in claim 1 for use in allergic diseases selected from asthma, allergic rhinitis, food allergies, atopic dermatitis, and anaphylaxis.
 8. Pharmaceutical compositions for the treatment of allergic diseases and for the treatment of hyperplasias and malignancies evolving cells expressing FcεRI receptor comprising of an active ingredient a chimeric protein as defined in claims 1-6 and a conventional adjuvant product.
 9. A pharmaceutical composition for the treatment of allergic diseases and for the treatment of hyperplasias and malignancies according to claim 8 wherein said composition is in a suitable form for injection (intra-veneous, intra-articular, sub-cutaneous, intramuscular, intra-peritoneal), intra-nasal, intra-thecal, intra-dermal, trans-dermal, inhalation, toppical application, oral administration, sustained release, or by any other route including the enteral route.
 10. A method for the preparation of a pharmaceutical composition as defined in claim 9 comprising genetically fusing the Fc region of the mouse IgE molecule to PE and adding if needed a conventional adjuvant product.
 11. A plasmid comprising a promoter operably linked to a DNA molecule encoding a peptide as defined in claims 1-5. 